AN INTERFEROMETER SYSTEM FOR A SEMICONDUCTOR EXPOSURE SYSTEM

摘要

An interferometer measuring system comprising two moveable members (30, 40) and a reference member (22) that may have significantly less movement, the group having a number of attached measurement mirrors (31, 32, 33, 34), interferometers (41, 42, 43, 44, 45, 46, 47, 48) for measuring position and two optical support blocks (50, 60) for the interferometers. The interferometers (41-48) are used to determine the measured optical path lengths to each of the moveable members (30, 40) and reference member (22) and these positions are used to calculate the misalignment, or error in the relative positions of the moveable members (30, 40) with respect to the reference member (22). This calculated error is then used to correct the misalignment by moving the appropriate members in the manner directed by the calculation.